Set Gitlab::Shell#create_repository as OPT_OUT

On .com repositories are created through Gitaly for a while now. For
customers this is not the case unless these have chosen to do so through
feature flags. By moving this to opt out, everyone will be using this.

This move is part of the migration issue
https://gitlab.com/gitlab-org/gitaly/issues/593

The bigger impact this commit will have is that tests that use a
repository through `FactoryBot.create(:project, :repository)` will now
use Gitaly to do so. As tests run on the same disk, or at least machine,
this will most probably slow them down.

lib/gitlab/shell.rb

@@ -75,7 +75,8 @@ module Gitlab
       relative_path = name.dup
       relative_path << '.git' unless relative_path.end_with?('.git')
 
-      gitaly_migrate(:create_repository) do |is_enabled|
+      gitaly_migrate(:create_repository,
+                     status: Gitlab::GitalyClient::MigrationStatus::OPT_OUT) do |is_enabled|
         if is_enabled
           repository = Gitlab::Git::Repository.new(storage, relative_path, '')
           repository.gitaly_repository_client.create_repository
@@ -85,7 +86,7 @@ module Gitlab
           Gitlab::Git::Repository.create(repo_path, bare: true, symlink_hooks_to: gitlab_shell_hooks_path)
         end
       end
-    rescue => err
+    rescue => err # Once the Rugged codes gets removes this can be improved
       Rails.logger.error("Failed to add repository #{storage}/#{name}: #{err}")
       false
     end
@@ -487,8 +488,8 @@ module Gitlab
       Gitlab.config.gitlab_shell.git_timeout
     end
 
-    def gitaly_migrate(method, &block)
-      Gitlab::GitalyClient.migrate(method, &block)
+    def gitaly_migrate(method, status: Gitlab::GitalyClient::MigrationStatus::OPT_IN, &block)
+      Gitlab::GitalyClient.migrate(method, status: status, &block)
     rescue GRPC::NotFound, GRPC::BadStatus => e
       # Old Popen code returns [Error, output] to the caller, so we
       # need to do the same here...